S-(ethylxanthoyl) o-(4-nitrophenyl) o-ethyl dithiophosphate



Patented Feb. 9, 1954 S- (ETHYLXANTHOYL) (4-NITROPHENYL) O-ETHYLDITHIOPHOSPHATE Henry Tolkmith, Midland, Mich., assignor to The DowChemical Company, Midland, Mich., a

corporation of Delaware No Drawing. Application April 21, 1953, SerialNo. 350,242

1 Claim. 1

The present invention is directed to S-(ethylxanthoyl) O-(4-nitrophenyl)O-ethyl dithiophosphate of the formula I ll/ Callsin an inert organicsolvent such as benzene or diethyl ether. 0f the alkali metal ethyla-tesfound useful in the reaction, it is preferred to employ the sodiumcompound.

In carrying out the reaction, the sodium ethylate is added with stirringto the S-(ethylxanthoyl) O (4-nitrophenyl dithiophosphoric chloridedispersed in the solvent and the resulting mixture heated for a periodof time at a temperature of from 35 to 80 C. In practice, it issometimes convenient to operate at the boiling temperature of thereaction mixture and under reflux. Temperatures substantially in excessof 80 C. for any appreciable period of time should be avoided, as thedesired product has a tendency to decompose at such temperature. Ifdesired, an alcoholic solution of the ethylate may be employed as astarting material. It has been found that the excess alcohol does notinterfere with the course of the reaction. Upon completion of thereaction, the mixture may be filtered and the filtrate distilled underreduced pressure at gradually increasing temperatures up to atemperature of 80 C. to separate low boiling constituents and to obtainas a residue the desired 8- ethylxanthoyl) O- (4-nitrophenyl) O-ethyldithiophosphate.

The S-(ethylxanthoyl) O-( i-nitrophenyl) dithiophosphoric chlorideemployed as a starting material in the above-described method may beprepared by reacting one molecular proportion of sodium l-nitrophenolatewith one molecular proportion of S-(ethylxanthoyl) dithiophosphoricdichloride in an inert organic solvent such as benzene. In carrying outthe reaction, the reactants are dispersed in the solvent and theresulting mixture heated for a period of time at a temperature of from35 to 80 C. To avoid decomposition, temperatures substantially in excessof 80 C. should not be employed. Upon completion of the reaction, themixture may be filtered and the filtrate concentrated by distillationunder reduced pressure to a temperature up to 80 C. to obtain as aresidue the desired S- (ethylxanthoyl) O-( l-nitrophenyl)dithiophosphoric chloride. This compound is a viscous oil having adensity of 1.4901 at 20 C. The latter compound and described method forits production constitute the subject matter of my copending applicationSerial No. 203,772.

In a representative preparation, an alcoholic solution of 6.8 grams (0.1mole) of sodium ethylate in milliliters of ethanol was added withstirring to 35 grams (0.1 mole) of S-(ethylxanthoyl) O-( i-nitrophenyl)dithiophosphoric chloride dispersed in 300 milliliters of diethyl etherand the resulting mixture heated for 6 hours at the boiling temperatureand under reflux. At the end of this period, the reaction mixture wasfiltered and the filtrate concentrated by distillation under reducedpressure to a temperature up to C. to obtain as a residue the desiredS-(ethylxanthoyl) O-(4-nitrophenyl) 0- ethyl dithiophosphate product.The latter is a viscous oil having a density of 1.3654 at 20 C. and

a refractive index n/D of 1.5587 at 25 C.

The new S-(ethylxanthoyl) o-( l-nitrophenyl) O-ethyl dithiophosphate poduct is effective as a parasiticide and adapted to be employed for thecontrol of a wide range of agricultural and household pests such asflies, mites, aphids, beetles and cockroaches. For such use, thecompound may be dispersed on an inert finely divided solid and employedas a dust. Also, such mixtures may be dispersed in water with the aid ofa dispersing and wetting agent and the resulting aqueous suspensionsemployed as sprays. In other procedures, the new product may be employedin oils, as a constituent in oil-in-water emulsions, or in waterdispersion with or without the addition of emulsifying, wetting ordispersing agents. Suitable concentrations of the toxicant in dusts arein the order of from about 0.1 to 10 percent by Weight of the dust andin liquid suspensions from about 0.1 to 3 pounds per gallons of thespray mixture. In illustrative operations against representative plantpests, 100 percent kills of two-spotted spider mites, bean aphids andMexican bean beetles were obtained with aqueous spray compositionscontaining 0.12, 0.5 and 0.12 pound, respectively, of

the toxic dithiophosphate per 100 gallons of spray mixture.

This is a continuation in part of my copending application Serial No.203,772, filed December 30, 1950.

I claim:

S-(ethylxanthoyl) O-( l-nitrophenyl) O-ethyl dithiophosphate.

HENRY 'IOLKMITH.

No references cited.

